Batman: Arkham City - Observation Deck

Start the battle by hanging off of one of the outside ledges and doing a ledge takedown. Use any neutralizing tools you may have (deactivate weapons, sonic baterangs). There are two ladders in the room, they always go up one and down the other. I found the best spot was by the ladder that goes up. If you go through the middle of the room, Dr. Strange can see you and will point you out so be mindful of that. Almost all of the dirty work will have to be done on the ground so make good use of crawl spaces and cover. If you are patient though, you should be able to catch a guard alone at that spot and do a silent takedown. However you go about it, there are five left (assuming you took out the guard by the ledge).

When you are done, climb that ladder and go to strange's door. Hack the panel with an awesome password and then confront Dr. Strange.